Eyes are important organs, which play a critical role in human's visual perception. An eye has a roughly spherical shape and includes multiple elements, such as cornea, lens, vitreous humour, and retina. Imperfections in these components can cause reduction or loss of vision. For example, too much or too little optical power in the eye can lead to blurring of the vision (e.g., near-sightedness and far-sightedness), and astigmatism can also cause blurring of the vision. Because the cornea is responsible for a significant portion of the eye's optical power, it is also important to accurately measure its topography. In addition, corneal topography provides important information for laser refractive surgery.
Both wavefront sensors and corneal topographers are important tools in ophthalmology. Wavefront sensors provide information indicating one or more aberrations in the eye. In particular, wavefront sensors have an advantage over auto-refractors in that wavefront sensors can measure higher order aberrations. Various corneal topographers (e.g., Placido topographers) are used for measuring the shape of cornea. An early intervention of visual impairment through an early diagnosis may allow reversal, or control over further progression of, such visual impairment. It is believed that almost 80% of visual impairment cases are preventable with proper diagnosis and intervention.
However, diagnostic instruments that can perform both wavefront sensing and corneal topography are not readily available, partly due to their sizes and costs. Especially, many children do not receive the eye care they need, and they are at the greatest risk of undetected vision problem. A portable device that can perform both wavefront sensing and corneal topography is expected to allow wider and more frequent screening for visual impairments, which will prevent a great number of visual impairment cases.